In the field of automotive safety, there are several systems that indicate the presence or motion of a vehicle to persons in the local area of the vehicle. For example, a horn can be used by the driver as a manually operated signal. Also, beepers or lights can be automatically activated, particularly upon shifting the vehicle into reverse. The one pervasive indicator of the presence of a vehicle is sound vibrations produced by the internal combustion engine, which can be detected by a person even from hundreds of feet away. Further, an indication of speed or acceleration of a vehicle can be determined from the engine sound.
However, electric vehicles can be very quiet in operation since they have no internal combustion engine to produce noticeable engine sounds. Hence, it becomes more difficult for persons in the vicinity to detect a vehicle. Therefore, a safety issue arises because of the lack of noise from an electric vehicle. For example, delivery vehicles generally pickup deliveries at a central hub or station. The central hub or station is often a dangerous place for workers and others because of the constant movement of vehicles. With internal combustion engines, workers are at least alerted by noise of approaching vehicles. However, electric vehicles may not provide the warning signal that internal combustion engines provide. Therefore, delivery workers would encounter a more dangerous loading environment using electric vehicles because of the lack of noise.
There have been efforts to emulate vehicle sounds. For instance, U.S. Pat. No. 5,237,617 to Miller (“Miller”) discloses a sound effects generator for a vehicle involving a signal synthesizer system. Miller is directed to imitating engine sound signatures of high-performance automobiles. Signals are generated in response to detectors that detect the operating conditions of a vehicle, such as the exhaust and throttle position. An analyzer receives the signals and combines and analyzes them to produce a digital signal representing the operating conditions of the vehicle. The output from the analyzer is applied over a lead to a digital synthesizer. Also, signal outputs from a microchip card processor are applied over a lead to the digital synthesizer. The microchip card processor may have a slot receptacle that can receive a programmed microchip card. The signals from the card and signals from the analyzer are combined to produce digital output signals that can be converted into analog signals. These analog signals can be run through speakers and produce sounds that emulate a vehicle.
Miller utilizes a digital synthesizer to produce sounds representative of a vehicle. However, the need still exists for a simplified vehicle enunciator that can produce sounds using sound data.